Demo: fork() and Copy-on-Write

Run

make
./fork_cow

Ask

• After fork() the child's Pss is half its Rss. What did fork() copy, and what did it not?
• Reading 64 MB cost 0 faults. Writing it cost 16,384. What happens in each of those?
• The parent's p[0] is still 1. Whose frames did the child write to?